1. Field of the Invention
The invention relates to a doctor blade device, also called a scraper device, for machines for the coating of fibrous webs.
2. Description of the Related Art
Devices of this type are generally known, in particular in the paper industry, for the coating of paper or cardboard or for keeping rotating rollers clean (see, for example, DE 198 41 637 A1). In this context, a leaf-shaped doctor blade or scraper element runs axially along a roller, the front end of the doctor blade element being pressed with a scraper edge against the surface of the roller. The doctor blade element is guided and held in a holding means. The holding means is generally designed to be pneumatically adjustable in the direction of the roller.
The doctor blade element is in this case mounted, for example via a multiplicity of pins, in a longitudinal groove of the holding means. When the doctor blade element, which is subjected to high wear, is exchanged, it is drawn out of the holding means laterally, that is to say axially parallel to the roller. A new doctor blade element is subsequently pushed into the holding means in the same way in the opposite direction.
This exchange has the disadvantage, however, that there are sometimes considerably difficulties in recovering the doctor blade element or scraper element from the holding means. The doctor blade element, due to operation, is often heavily soiled and is stuck to the holding means. As a result, considerable forces have to be exerted by the operator in order to pull the doctor blade element out of the holding means.
One problem, here, is that considerable sliding lengths are involved, since the length of the rollers and therefore also of the doctor blade element amounts to several meters. Furthermore, the application area for the pulling forces to be exerted is restricted to the narrow front region of the doctor blade element with which the latter projects from the holding means. Since the exchange work is carried out several meters above the floor of a scaffold or platform, there is consequently also a high risk of accidents when the exchange of the doctor blade element presents difficulties because of heavy soiling and/or stubborn sticking.
The object on which the present invention is based, therefore, is to provide a doctor blade device, in which the doctor blade element can be exchanged essentially reliably by relative simple means.
This object is achieved, according to the invention, by means of a doctor blade device for machines for the coating of fibrous webs, in particular of paper or cardboard, and for keeping rotating rollers clean, with a leaf-shaped doctor blade element which is held by a holding means and which, for a change, can be drawn out laterally on the holding means, wherein the doctor blade element is provided at least on one side with a grip part.
By virtue of the grip part according to the invention, then, a separate region or part on the doctor blade element is provided, which may be provided specially for the exchange operation.
When, in an advantageous refinement of the invention, there is provision for the grip part to be located outside the normal working range, for example in a corresponding prolongation of the doctor blade element, it can then be adapted optimally to the set object. This applies, for example, with regard to appropriate grip and size. Moreover, the most diverse possible driving and retaining members can be provided on or in the grip part in a simple way.
For example, a bore, into which a push-out tool appropriately engages with a mandrel or pin, can be introduced in the grip part in a simple way. A very reliable and positive connection is thereby afforded, with the result that, even in the case of high resistance forces which occur, for example, because of heavy soiling and resulting sticking, it becomes possible for the doctor blade element to be exchanged to be pulled out.
Conversely, of course, it is also possible for the grip part to be provided with corresponding elevations, abutments, shoulders, bosses or pins and the like, on which or in which a push-out tool can engage with a corresponding countermember, for example a lug.
In a highly advantageous refinement of the invention, there may be provision for the width of the grip part to correspond at least approximately to the width of the holding means. In this case, the front region of the doctor blade element remains unchanged for its satisfactory functioning. The region with which the grip part projects laterally from the holding means is generally fully sufficient for this region to be capable of being used as a grip part.
Further advantageous refinements and developments may be gathered from the remaining subclaims and from the exemplary embodiment described in principle below with reference to the drawing in which: